The present invention relates to a composite metal material and a method of producing the same, a caliper body, a bracket, a disk rotor, a drum, and a knuckle for vehicles.
A composite material using carbon nanofibers has attracted attention. Such a composite material is expected to exhibit improved mechanical strength due to inclusion of the carbon nanofibers.
As a casting method for a metal composite material, a casting method which causes magnesium vapor to permeate and become dispersed in a porous formed product of oxide ceramics while introducing nitrogen gas to cause a molten metal to permeate the porous formed product has been proposed (e.g. JP-A-10-183269).
However, since the carbon nanofibers have strong aggregating properties, it is very difficult to uniformly disperse the carbon nanofibers in the matrix of the composite material. Moreover, the carbon nanofibers have insufficient wettability with a matrix such as a metal material. Therefore, it is difficult to obtain a carbon nanofiber composite material having desired properties. Moreover, expensive carbon nanofibers cannot be efficiently utilized.
In addition, since the related-art casting method which causes a molten metal to permeate the porous formed product of oxide ceramics involves complicated processing, production on an industrial scale is difficult.